Adds support for properties in business process definitions

PropertiesAwareProcessDefinitionResource.java

package ru.teamidea.utils.process;

import de.hybris.platform.processengine.definition.ProcessDefinitionResource;
import de.hybris.platform.util.Config;
import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.InputStreamResource;
import org.springframework.core.io.Resource;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.lang.ref.SoftReference;
import java.nio.charset.StandardCharsets;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Created by Timofey Klyubin on 07.04.17
 */
public class PropertiesAwareProcessDefinitionResource extends ProcessDefinitionResource {

    @SuppressWarnings("unused")
    private static final Logger LOGGER = LoggerFactory.getLogger(PropertiesAwareProcessDefinitionResource.class);

    private static final Pattern propertiesRegex = Pattern.compile("\\$\\{([^}]+)\\}");
    private static final char ESCAPE = '$';

    private Resource initialResource;
    private SoftReference<Resource> cachedResource;
    private boolean changed = false;
    private final Map<String,String> paramsCache;

    public PropertiesAwareProcessDefinitionResource() {
        super();
        paramsCache = Config.getAllParameters();
    }

    public PropertiesAwareProcessDefinitionResource(final Map<String, String> paramMap) {
        super();
        paramsCache = paramMap;
    }

    private Resource proceedWithResource() {
        final String xmlDefinition;
        try {
            xmlDefinition = IOUtils.toString(initialResource.getInputStream(), StandardCharsets.UTF_8);
        } catch (IOException e) {
            LOGGER.error("Couldn't read resource [".concat(initialResource.getFilename()).concat("]"), e);
            throw new RuntimeException(e);
        }
        final StringBuilder output = new StringBuilder(xmlDefinition);
        final Matcher propMatcher = propertiesRegex.matcher(xmlDefinition);
        int offset = 0;

        while(propMatcher.find()) {
            final String propKey = propMatcher.group(1);
            final String value = paramsCache.get(propKey);
            if (value != null && output.charAt(propMatcher.start() + offset - 1) != ESCAPE) {
                output.replace(propMatcher.start() + offset, propMatcher.end() + offset, value);
                offset += value.length() - propMatcher.end() + propMatcher.start();
            }
        }

        return new InputStreamResource(new ByteArrayInputStream(output.toString().getBytes(StandardCharsets.UTF_8)));
    }

    @Override
    public void setResource(Resource resource) {
        this.initialResource = resource;
        this.changed = true;
    }

    @Override
    public Resource getResource() {
        if (changed) {
            this.changed = false;
            this.cachedResource = new SoftReference<>(proceedWithResource());
            return this.cachedResource.get();
        }
        if (this.cachedResource.get() != null) {
            return this.cachedResource.get();
        }
        this.changed = true;
        return this.getResource();
    }
}